Prosthesis and method therefor

ABSTRACT

Improved prosthetic components and a method for assembly therefor are described wherein the prosthesis comprises prefabricated modular components including a socket adapter, shank or pylon, a keel, and a foot. The method for preparation of the improved prosthesis reduces the time required for prosthesis preparation over that of the prior art, and includes the steps of making a cast of the remaining leg stump and forming a socket therefor; placing the socket in an alignment jig; assembling modular pieces including a prefabricated keel, pylon, and socket adapter; attaching the socket adapter to the socket; draping a final coating of copolymer on the prosthesis; and removing the pylon and socket adapter from the interior of the prosthesis.

FIELD OF THE INVENTION

[0001] This invention is directed to artificial prosthetic componentsand assembly methods therefor for use in a human lower limb prosthesis.More particularly, this invention is directed to improved humanprostheses and methods therefor wherein the prosthesis comprises modularprefabricated components.

DESCRIPTION OF RELATED ART

[0002] The most common artificial leg for below knee amputees is of arigid nature. A solid shank connects the socket, which mounts theartificial leg to the residual limb of the amputee, and the artificialfoot. The shank is often made out of a rigid alloy, such as onecontaining titanium, or from shaped wood or plastic. It can be solid forstrength, or it can be hollow for lightness.

[0003] In a typical conventional prosthesis fabrication technique, asignificant amount of time and effort is wasted in duplicatingfabrication steps. Generally, conventional fabrication includes taking acast of the patient's stump and making a socket incorporating thenecessary fittings, including (a) an alignment fitting for angularadjustments; (b) a tubular fitting for length and rotational adjustment;(c) a fitting for linear adjustments; and (d) an ankle fitting forangular adjustments and to allow attachment of a foot. The prosthesis isassembled for bench alignment and the patient is scheduled for dynamicalignment. When the patient and prosthesis are satisfied with both thefit of the socket and the alignment of the prosthesis, the prosthesis isduplicated in an alignment device that captures the prosthetic alignmentand allows removal of the metal components and replacing them withpolyurethane. The area between the top of the keel and the bottom of thesocket is foamed in place, and when the foam hardens, the shank is handshaped to the desired configuration between the keel and the socket. Theprosthesis is prepared for the final draping of copolymer plastic. Ifthe finished prosthesis is not satisfactory and can not be adjusted, theprocess is repeated using the same components. The approximatefabrication time for this procedure is 5 to 8 hours.

[0004] As an example, U.S. Pat. No. 4,314,398 discloses a method ofmaking a lower leg prosthesis comprising the steps of (a) forming atemporary prosthesis socket having an inner shape corresponding to theremaining lower leg stump of the amputee to which the prosthesis is tobe attached; (b) forming a test prosthesis by fixing an adjustableposition testing device to the temporary socket and connecting thetesting device to the prosthesis foot through a temporary connectingmember; (c) testing the test prosthesis on the patient and adjusting thetesting device so as to obtain a proper alignment of the temporarysocket in relation to the prosthesis foot; (d) providing a positiveprosthesis socket in the temporary socket of the test prosthesis andreproducibly fixing the assembly comprised of the positive socket, thetemporary socket, the testing device and at least the temporaryconnecting member in a support device; (e) removing the test prosthesisparts from the support device; (f) placing the connecting memberadjacent the positive socket in the support device in the alignedrelative position reproducibly set in the support device in step (d);and (g) forming the prosthesis socket on the positive socket whilesimultaneously securing the connecting member to the prosthesis socketin the aligned relationship thereby obtaining an individually alignedlower leg prosthesis. However, the method associated with this referencerequires duplicating assembly steps; i.e., fixing the adjustableposition testing device to a temporary socket and temporarily connectingthis device to the prosthesis foot, followed by removing the testprosthesis and replacing it with a permanent member in the positionformerly occupied by the testing device.

[0005] U.S. Pat. No. 5,152,800 discloses a below the knee prosthesis andmethod for making the same. The prosthesis includes a socket forreceiving the stump of the below-the-knee amputee, a keel having aperipheral groove formed about the periphery of a bottom portion of thekeel, a tubular shin member extending from the socket and surroundinglateral and medial portions of the keel and filling the peripheralgrooves formed about the bottom portion of the keel leaving asubstantial portion of the bottom of the keel exposed. A resilient footmember is then secured to the exposed portion of the keel with thematerial of the tubular shin member being formed into the grooves of thekeel and maintaining such keel within the shin member. The methodthereof includes the steps of forming a socket for receiving a stump ofthe below-the-knee amputee; constructing a shin support about the socketincluding an ankle block and keel about the socket in accordance withthe size and stature of the amputee; forming a retaining means in abottom surface of the keel for retaining the keel in a predeterminedposition with respect to the socket; molding a sheet of copolymermaterial about the shin support, into the retaining means and over thebottom surface of the keel to form a shin member; removing the copolymermaterial from the bottom surface of the keel; removing a substantialportion of material used to construct the shin support from within theshin member; and securing a foot member to the keel. The method forassembly of this device does not take advantage of a prefabricatedsocket adapter/pylon/keel assembly, instead requiring several distinctsteps for assembling the prosthesis including assembling a shin supportbetween the socket adapter and the keel, foaming the support, draping acopolymer exterior on the assembly, and drilling out the foam shinsupport.

[0006] The prior art also includes continuous one-piece prostheses, suchas that shown in U.S. Pat. No. 5,219,364. That prosthesis offers theadvantages of light weight and improved energy storage and releasecharacteristics. Because of its design, however, this prosthesis canrequire multiple patient trips to the prosthetist for fitting. Incertain cases the patient may have to be fitted with another prosthesiswhich will be adjusted for various parameters, including height, pylonlength, inversion, and eversion. Once the prosthesis is adjusted, themeasurements from the adjusted prosthesis are then used to form theone-piece prosthesis, following a time consuming process. Further, oncethe prosthesis is manufactured, adjustments may require reheating andreforming the prosthesis.

[0007] U.S. Pat. No. 5,993,487 discloses a prosthetic component for usein a human lower limb prosthesis. The component consists of an preformedintegrated pylon-keel or foot component. In practice, the prosthetistwould perform a stump measurement on the amputee to determine theoverall height of the prosthesis from which the pylon length could bedetermined, then cut a preformed integrated pylon keel prosthesis to fitthe pylon to an adjustable tube clamp, whereby the clamp itself issecured to the socket. Then the prosthetist adjusts the tube clamp forinversion eversion, foot position, and rotation, then the integratedpylon/keel is attached to the tube clamp and the apparatus is coveredwith plastic. However, this is not a complete prosthesis, but merely thepylon/keel assembly. Further, the invention requires the use of anadjustable tube clamp attached to the socket. This additional componentadds complexity and weight to the structure. Moreover, because the keeland pylon are an integrated unit, an inventory that could allow for thenaturally occurring variety of needed keel sizes and pylon lengths wouldrequire an extremely large assortment of integrated keel/pylon units.

[0008] It would be advantageous to provide an improved method andprosthesis therefor that avoids the problems associated with the priorart. It would further be advantageous to provide a lightweight modularprosthesis and a method of assembly therefor that can be assembled in asingle sequence of steps, maximizing simplicity and minimizing the timeexpended by the wearer in achieving an acceptable fit.

SUMMARY OF THE INVENTION

[0009] The difficulties associated with the prior art are overcome byproviding an improved prosthetic component and method for assemblywherein the prosthesis comprises prefabricated modular componentsincluding a socket adapter, shank or pylon, a keel, and a foot. Themethod for preparation of the improved prosthesis reduces the timerequired for prosthesis preparation over that of the prior art, andincludes the steps of making a cast of the remaining leg stump andforming a socket therefor; placing the socket in an alignment jig;selecting and assembling a prefabricated keel, pylon, and socketadapter; shaping the socket adapter to a desired configuration;attaching the socket adapter to the socket; draping a final coating ofcopolymer on the interior pieces, and removing the pylon and socketadapter. There is a single method of adjustment of the prosthesis, whichis accomplished by presetting the position of the foot prior toattaching the socket adapter/pylon/keel to the socket. The connectingface of the socket adapter is shaped to incorporate the proper alignmentbetween the socket and the keel, and the length of the pylon is selectedto provide the proper length of the prosthesis. The approximatefabrication time for this method is less than one hour, which is asubstantial time savings per unit. Because of the reduced preparationtime, should the prosthesis prove unsatisfactory, which is common inprosthesis manufacturing, making another prosthesis results in much lesswasted man hours.

[0010] A solid cast of the residual stump is made in a standard method.When making this cast, a hollow tube or pipe is put in the cast, whichprovides a basis for vacuum forming a polymer socket over the cast. Thesocket is allowed to cool and harden, and the plaster is removed. Afterthis, another pipe is held in a correct position in the socket, and anew cast is poured using the socket as a mold.

[0011] The socket is supported by the pipe and set up in a support jiguntil proper orientation is achieved. This can be achieved by aligningand bending the metal pipe to a proper orientation. After this, theappropriate keel, pylon, and socket adapter are selected and assembledunder the properly oriented socket. The components are glued to eachother, and the assembled keel/pylon/socket adapter is then placed in thecorrect orientation to the socket and bonded to the socket using rigidfoam.

[0012] The unit is then removed from the alignment jig, and a majorityof the socket is cut away from the cast. The cast then receives anydesired modifications. The final coating of copolymer is then applied tothe unit, shaped, and allowed to cool and harden. After this step, thepylon, socket adapter, and socket are removed from the shell, and thesocket is then returned to the shell and secured. The foot is then gluedto the keel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The detailed description is best understood by reference to thefollowing figures, in which:

[0014]FIG. 1 is a side elevational view of a typical lower legprosthesis;

[0015]FIG. 2 is a side elevational view of a semi-completed prosthesis,including intermediate components used in an embodiment of a method ofthe present invention;

[0016]FIG. 3 is side view of a pylon according to an embodiment of thepresent invention;

[0017]FIG. 4 is a side elevational view of a semi-completed prosthesis,including intermediate components used in an embodiment of a method ofthe present invention;

[0018]FIG. 5 is side elevational view of a nearly completed prosthesis,including intermediate components used in an embodiment of a method ofthe present invention;

DETAILED DESCRIPTION OF THE INVENTION

[0019] Referring first to FIG. 1, a prosthetic device 100 isillustrated. The preferred prosthetic device is designed to replicatecertain functional aspects of the human leg, especially for lower limbamputees. The prosthetic device 100 is configured to fit over a residualstump 105 of a limb. The preferred adaptation is with a socket 110,which is made to ultimately conform to the shape of the stump 105. Atthe lower end, the keel 115 replicates the structure of the foot, andgenerally has a foot prosthesis 120 of suitable shape attached tofurther imitate the appearance and functional characteristics of a humanfoot. The shank 125 of the prosthesis is a generally vertical componentfunctioning to transmit forces between the residual limb, or stump, ofthe amputee and the keel 105.

[0020] During the fabrication of a prosthetic device, intermediatecomponents are needed prior to the final draping, or drop, of theexterior of a prosthesis. FIG. 2 is a side elevational view ofintermediate components used in an embodiment of a method of the presentinvention. In this view, the keel 115 and foot 120 portions are alreadyassembled together. Projecting from the keel 115 is a pylon 205, whichlongitudinally fixes the keel from the socket 110. Topping the pylon 205is a socket adapter 210, which adapts the pylon 205 to the socket 110.The socket 110 is made to conform to the residual stump 105 of thepatient. This socket 110 is also referred to as a cup, which becomesmore apparent toward the end of the assembly procedure when it istrimmed to height of only a few inches. This socket 110 will be removedfrom the interior of the prosthesis 100 at the same time as the pylon205 and socket adapter 210, but it will be replaced and secured in theprosthesis 100 following removal of the pylon 205 and socket adapter210.

[0021] The pylon 205 is shown with a square cross section, but any crosssection that provides suitable strength may be used. Additionally, thepylon 205 can be hollow or solid. However, since one of the benefits ofthis invention is to enhance ease and speed of assembly, the shapeshould be that which enables simple fabrication and handling of thepylon 205.

[0022] In FIG. 3, the pylon is shown in isolation. It is shown with asquare cross section, which facilitates production. The diameter of thepylon is sized to fit inside the shank of the prosthesis, preferably onthe order of approximately one inch. One end 305 of the pylon 205 issmaller than the general diameter of the pylon, approximately ⅞ inch, sothat it can fit into a similarly sized female hole in the keel 115. Theopposite end 310 is not so sized, and therefore may fit into anapproximate one inch female hole in the socket adapter 210, and may becut down in length without affecting its fit. FIG. 4 shows the reducedend 305 and the opposite end 310 of the pylon in an assembled positionbetween the socket adapter 210 and the keel 115.

[0023] A complete method according to an embodiment of the presentinvention for production of a prosthesis is hereinafter described.

[0024] Cast Preparation for Initial Drop

[0025] An exterior negative cast of the stump is made in any standardmanner. This can be accomplished by surrounding the stump with plasterof Paris, allowing the mold to dry, and carefully removing the negativemold from the stump. This negative mold is then filled with plaster tocreate a mold of the stump. A hollow metal pipe, which will be theprimary conduit for applying vacuum for the initial drop, is placed inthe plaster extending outward. After drying, the exterior negative moldis removed, leaving a positive cast of the stump with the hollow pipeextending therefrom.

[0026] Two small holes are drilled in the pipe within 1.5 inches fromtop of the cast. The holes are then covered with screen to allow airevacuation, and to prevent the later-applied plastic from sealing offthe holes. The top of the cast is covered with Dacron felt adhered withspray adhesive. The cast is placed in a vise and a vacuum hose isconnected to the pipe. At this point, the popliteal should be faced downtowards the floor.

[0027] Preferably, ⅛-inch thick copolymer plastic is used to fabricatethe socket 110, which is shown in FIG. 2. Copolymer of natural or anyflesh tone color can be used for this socket as long as is consistentwith between 90/10 and 93/7 ratio of polypropylene and polyethylene.

[0028] A plastic sheet is cut to a width six inches greater than thecircumference of stump, and a length of six inches longer than thelength of the socket. The plastic is cleaned and deburred, and aligningmarks made on the center of bottom and top of plastic with a marker,which will aid in centering the plastic over the cast when molding.

[0029] The plastic is then placed in an oven at an appropriatetemperature to render it pliable. This will vary depending on theparticular plastic composition, but is generally around 400° F. Therequired heating time will vary according to thickness of the plastic,but will generally be between 8-24 minutes. Immediately prior to removalof the plastic from the oven, nylon knee high panty hose material issaturated with silicone oil and pulled over the cast with the seamplaced laterally to medially on the distal end. The nylon stockingfunctions to maintain air passages along the surface of the cast. Theseair passages reduce the chances of bubbles forming in the socket bypockets of air trapped between the copolymer sheet and the mandrelassembly and hence allow a more definite conformance of the copolymersheet to the cast. Further, the nylon stocking aids in removing thesocket from the cast. The plastic is removed from the oven whenappropriate and is aligned over the center of the cast using thepreviously made marks. The plastic is carefully draped while avoidingany stretching or drooping, and is manually sealed around the cast andpipe to ensure tightness of the vacuum, which should be pulling between10 and 20 pounds of pressure. The seam of the plastic is trimmed ¼-inchand the distal end of the seam is rolled with a 1-inch dowel rod for asmoother distal end cap.

[0030] The plastic is allowed to cool for approximately 15 minutes andis then removed from the cast using the following method. The plastic iscut with a cast saw around the entire superior edge of the socket. Thesocket is then removed from the cast by either blowing it off or by theconventional method of breaking out the cast. Socket removal by airpressure is preferred for casts conical in shape and without prominentundercuts. For this method, a small hole is drilled through the distalend of the socket and liner. The positive model is secured in a vise,and a nozzle of an air pistol is placed against the hole. When pressureis applied, the socket should pop off the cast. Tapping of the superiorrim of the socket with a hammer against a block of wood may be used instubborn cases.

[0031] The proximal edge of the socket is trimmed flat, and the distalend of socket is then prepared for foaming by using a router to roughenthe area that will be contacting the socket adapter.

[0032] Pouring the Socket

[0033] The inside of the socket, which will now function as a mold foranother plaster cast, is lightly powdered. Marks are made mid line onthe lateral side of the socket and mid line on the posterior aspect ofsocket.

[0034] A hollow metal pipe is positioned to extend to at least 16 inchesfrom the top of the socket. The socket is positioned to be filledvertically on a level surface in 1 degree of flexion (the crest of thetibia is the guideline for this). The pipe is centered in the socket andaligned to the center lateral and posterior lines previously marked onthe socket. The pipe should also be positioned in the center of thesocket as well as being perpendicular to the flat surface that thesocket is on. A small level may be used to achieve this. The new plastercast is slowly poured, maintaining the pipe position, and allowed to setup.

[0035] Aligning Socket in Vertical Jig

[0036] A collar is temporarily placed on the pipe approximately threeinches from the top. The socket is placed in a vertical jig and checkedfor alignment so that the socket's popliteal area is parallel to theline of progression. At this point, if the abduction or adduction is notcorrect the pipe is bent until corrected, then the unit is remounted inthe jig. It is important to make adjustments one at a time until thecorrect alignment is achieved.

[0037] The center of the patella tendon is marked on the socket so thatthe patella tendon line is the same height to the base of the verticaljig as the anatomical height of the patella tendon recorded from thepatient's sound extremity. The distance from the bottom of the socket tothe base of the vertical jig is measured, and this number minus one inchis recorded.

[0038] Assembling the Components

[0039] The foot is placed on a ½-inch heel wedge directly under thesocket, which is being held in the jig. The keel is inserted into thefoot so that the alignment square on foot is in the square hole in keel.The pylon is then inserted into the keel, and the socket adapter placedover the other end of the pylon.

[0040] When the components are assembled but not yet glued, the lengthof the prosthesis from the bottom of the foot as it stands on the benchto the top of the socket adapter is measured. The previously recordedmeasurement taken from bottom of the socket to the base of vertical jigis subtracted from the prosthesis length. The remainder is cut off thelength of the top of the pylon after removing the socket adapter. Thecomponents are reassembled and placed under the socket on the verticaljig base with the ½-inch heel wedge in place. At this point, thereshould be approximately ¼ inch between the bottom of the socket and theinside of the socket adapter.

[0041] The components are disassembled and both ends of the pylon arelightly sanded where they fit into the keel and socket adapter. Theinside of the well on the socket adapter is roughed up with a cone onthe router, which will ensure good bonding between the distal end of thesocket and the inside of the socket adapter. A small amount of 10-minuteepoxy is used to bond keel and socket adapter to the pylon.

[0042] Aligning and Attaching Assembled Components to the Socket

[0043] The assembled components are placed under the socket with the½-inch heel wedge in place. The foot is then turned to achieve correcttoe out. The mid center lateral line is aligned so it is in alignment tothe point where the lateral corner of the keel and pylon meet. A ruleror plumb line are helpful in this regard. The posterior mid linepreviously marked on the socket is aligned so that the point where thepylon inserts into the keel is ½ inch medially to the socket. Thisshould be done while still maintaining the correct toe out.

[0044] Bonding the Components to the Socket

[0045] After alignment is achieved, the foot is secured and a smallamount of rigid foam is slowly poured into the well of the socket pylonadapter. The foot should not be released until the foam starts tosolidify. The foam should be allowed to harden before moving the unit.

[0046] Preparing for Final Drop

[0047] The prosthesis is removed from the vertical alignment jig. Thearea where the plastic socket begins an inward flair on the distal endis located; some foam might have to be removed to find this point. Oneach of the medial and lateral sides a dowel hole is drilled at a45-degree angle through the plastic into the cast approximately one totwo inches in depth.

[0048] The socket is then split medially using the cast saw to removethe socket from the cast. Sometimes a lateral split is needed as well.The socket should not be cut within one inch of the dowel holes.

[0049] At this time the semi-completed prosthesis can be checked on alevel surface, with the heel wedge in place or in the shoe. If changesare needed, the pylon is heated and manipulated as necessary. If linearchanges are required the pylon can be cut (usually at the thickest partof the socket adapter), moved as necessary and rebonded with 10-minuteepoxy.

[0050] Preparing Distal End and Finalizing

[0051] A cast saw is used to cut through entire socket, at the distalend approximately ¼ inch above the dowel holes. The part of the socketthat remains is referred to as a cap. The outer edge of the cap is thensanded to a thickness of {fraction (1/32)} inch at its proximal edge.Two 5-inch dowels ({fraction (3/16)}-inch diameter) are cut and one endof each is sharpened to a point in, for example, a pencil sharpener.With the cap replaced on the cast, the holes are aligned and the dowelscan be gently tapped through the cap into the cast until they bottomout. The dowels are cut flush and the ends mushroomed to hold theprosthesis on the cast.

[0052] At this time the cast above the distal end cap may be modified asneeded, for example, for fibula head relief or distal tibia.

[0053]FIG. 4 shows a semi-completed prosthesis that has been preparedfor the final drop. The plaster cast 405 is clearly visible in the capor socket 110, which has been cut down according to the above steps.

[0054] The cast is placed in a horizontal position and plaster is usedto smooth any irregularities and transitions in the foam. The plastershould be allowed to dry before lightly sanding.

[0055] Preparation for vacuum forming includes drilling two small holesin the pipe as close to the top of the cast as possible. These holes arecovered with two layers of sanding screen and taped in place. For thefinal drop, {fraction (3/16)}-inch plastic is cut to the followingmeasurements: top width=circumference+6 inches; bottom width=15 inches;length=prosthesis length+6 inches.

[0056] The plastic is cleaned and deburred and the center of the top andbottom are marked to assist in centering plastic during the drop.

[0057] To assist the eventual removal of the inner foam core, thefollowing procedure is used. Using clean dry panty hose, the toe is tiedin a knot and the excess is cut away. The panty hose is placed over amodel with the knot kept in the center portion of the proximal keel.Once in place a piece of aluminum foil large enough to encircle thepylon from just below the top of the cap to within 1 inch of the base ofthe keel is pressed around the pylon and the excess removed. Over thisis placed another nylon in the same manner as above. A plastic bag ispulled over the entire model and vacuum applied. This assists in removalof wrinkles from the foil. The bag is then removed.

[0058] A small indentation in the center lower portion of the base ofthe keel is created using an awl. Secondary vacuum is connected bypushing a metal vacuum rod tip into the indentation. A thin strip ofDacron felt interlaced with screen is attached to the rod to prevent theair vacuum from being sealed off.

[0059] A reinforcement strut of ¼-inch×{fraction (3/16)}-inch copolymercan be added to the prosthesis for additional strength, if needed. It isput in place at the same time as the initial drop, and runs the anteriorlength of the prosthesis from one inch above the distal tibia to centerof the dorsum of the keel.

[0060] Once the plastic has heated to temperature, the vacuum is turnedon. The heated plastic is removed from the oven and positioned over theprosthesis from near the top of the cast to the keel, aligning centermarks on the center of the prosthesis. The plastic is allowed to conformto the contours. Once the vacuum has sealed the plastic, the posteriorseam is cut within 1 inch of the prosthesis. A cut is then madeperpendicular to and through the seam on the underside of the primarypipe, and the secondary pipe is tied off with nylon cord.

[0061]FIG. 5 is side elevational view of a nearly completed prosthesis,including intermediate components used in an embodiment of a method ofthe present invention,. and shows the final polymer coating 505 over thesupporting structure, which includes the cast 405, the socket 110,socket adapter 210, pylon 205, and keel 115. The foot 120 is show forreference purposes; it gets permanently attached during the next step.

[0062] Preparing the Prosthesis for Bonding of the Foot

[0063] Once the plastic has cooled for at least 20 minutes, it isdisconnected from the primary and secondary vacuums. A cast saw is usedto cut around the perimeter of the socket above the trim lines exposingthe plaster, which is then chiseled out. A belt sander can be used toreduce the posterior seam to the appropriate size considering patientweight and activity level. The posterior seam should generally berounded and reduced to {fraction (1/32)} inch at the top of thepopliteal area. On heavier or more active patients the seam ispreferably at least ¼ inch.

[0064] The plastic on the bottom of the keel is removed using the beltsander to expose the two raised segments of foam. The periphery and theapex of the keel are then roughened with a 36-grit cone on low speed.

[0065] A rounded edged ⅞-inch spade bit is used to drill through thekeel at the dimple on the bottom until the space in the keel where thepylon inserts into the keel is reached. Epoxy on the base of the pylonshould be visible at this point. A ½-inch solid pipe can be used in thishole to drive the foam pylon, socket adapter and cap from the prosthesisthrough the inside of the socket. The foam in the base of the keel isthen hollowed out using a small acorn bit. It is important to that thediameter of the hole created by the spade bit is kept as small aspossible. A screwdriver may assist in removal of the foam. The excessfoam is removed from the cap and the cap replaced in the prosthesis andis wet-glued in place using a barge cement.

[0066] The “skin” is removed from the bottom of keel and a cross patternof cuts no deeper than {fraction (3/32)} inch is made on all exposedsurfaces on the keel bottom.

[0067] Bonding the Foot

[0068] With the foot on prosthesis and the assembly on a ½-inch heelwedge the foot and prosthesis are held firmly in place. The area aroundthe rubber flange encircling the keel is marked and the foot removed.Methyl ethyl ketone is used to wipe the foot clean, particularly in thewell area, and the foot is allowed to dry.

[0069] Epoxy is applied between the foot and the prosthesis, and theassembly is placed in a bag and vacuum attached. With the toe flat onthe work surface, the epoxy is allowed to cure.

[0070] The above method may also be adapted for transferring a fittingprosthesis. In this option, a piece of natural copolymer is attached tothe base platform of the vertical alignment jig. The prosthesis that isto be transferred is centered on the platform with a ½-inch heel wedgeunder the heel, and the socket is poured using a pipe with a collarattached and inserted in the jig. After the plaster has hardened theoutline of the foot is traced on the plastic platform. The height of thecollar as it is attached to the main strut of the vertical alignment jigis noted, the prosthesis is removed from the jig, and the socket isremoved from the cast. The socket is dropped in ⅛-inch copolymer andthen the complete method above is employed. The alignment must belengthened ½ inch from the height at which it was poured.

[0071] While the above detailed description describes the preferredembodiments of the present invention, it will be understood that thepresent invention is susceptible to modification, variation andalteration without deviating from the scope of the fair meaning of thesubjoined claims.

What is claimed is:
 1. A method for constructing a prosthesis forplacement on a remaining stump of a human limb, comprising the steps of:making a cast of the remaining stump and forming a socket therefor;selecting appropriate prefabricated modular components including atleast a keel, a pylon, and a socket adapter; assembling saidprefabricated components; adjusting a relative angle between said socketand said keel; attaching said socket adapter to said socket; draping acoating of copolymer over said assembled keel, pylon, socket adapter,and socket; and removing substantially all of said pylon and socketadapter from an interior of said coating of copolymer.